The overall aim of the proposed observational study is to continue population-based surveillance for monitoring trends in the incidence, management strategies, and recurrence and case-fatality rates associated with venous thromboembolism (VTE) in residents of a large metropolitan area. We will also perform prospective follow-up of a subset of patients diagnosed with VTE in 2009 and 2011. Despite advances in the diagnosis, prophylaxis, and treatment of this clinical syndrome, which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), VTE remains a significant cause of morbidity and mortality. Based on data from our initial study, the rates of recurrence of VTE after an initial diagnosis and the rates of bleeding related to VTE treatment remain unacceptably high. It has been estimated that annual mortality from VTE in Americans exceeds that of AIDS, breast cancer, and highway fatalities combined. This surveillance project will continue the follow-up of all residents of Worcester, MA diagnosed with DVT and/or PE during our 3 previous study years (1999, 2001, and 2003) with extension to 4 new study years (2005, 2007, 2009, and 2011). The overlapping components of this community-based study have been designed to provide complementary and inclusive information about the contemporary epidemiology of VTE including incidence rates, outcomes, physician management practices, and health-related quality of life (QOL), and changes over time therein. Detailed follow-up of our prospective cohorts will allow for more in-depth analysis of the natural history of VTE, its impact on health related QOL, duration and intensity of anticoagulation therapies employed, and evaluation of long-term medical care utilization patterns. The data provided from this study will be instrumental in identifying populations of patients with VTE at high risk for adverse outcomes, improper or underutilization of specific diagnostic testing or therapies, and contemporary outcomes. This information will set the stage for the design of targeted interventions to address shortcomings in current management practices with the goal of favorably influencing the long-term outcomes of patients with VTE. PUBLIC HEALTH RELEVANCE: It has been estimated that blood clots of the legs and lungs cause more deaths per year than AIDS, breast cancer, and highway fatalities combined. Data obtained from this study will allow for better estimates of the true burden of this disease in the U.S. as well as deficiencies in current management practices. This information will set the stage for future studies designed to address these shortcomings.